Various methods and apparatus have been heretofore developed for making said expandable honeycomb panels. Most, if not all, of these methods leave much to be desired from the standpoint of production efficiency.
Dutch Application Serial No. 6706563 of Landa, published Nov. 11, 1968 discloses the formation of such a panel from a number of narrow webs of thermoplastic material each of which are unwound from a roll in an unfolded state. The longitudinal edges of each web are tightly folded over, an end strip of a given length is then severed from each web, and the severed strips are then simultaneously superimposed. The superimposed strips are then welded together to form an expandable honeycomb panel.
Judge, Jr. U.S. Pat. No. 3,493,450 discloses a method of making expandable honeycomb panels by applying laterally extending bands of adhesive to a web of sheet material and cutting individual strips from the web. A vacuum pick-up device picks up the severed and adhesive coated strips of material and sequentially delivers the individual strips above a stacking station where they are stacked one upon the other. In the process of being stacked, the adhesive adheres the adjacent strips together to form an expandable honeycomb panel structure. The completed honeycomb structure is then cut into narrow strips of a desired width to form expandable honeycomb panels.
Colson U.S. Pat. No. 4,450,027 discloses another method and apparatus for making expandable honeycomb insulation panels. Like the method disclosed in the Judge, Jr. Patent, the Colson method starts with a continuous web of unfolded material and, like the method disclosed in the Landa published application, progressively folds over the opposite longitudinal edges of the web. The Colson method then applies a continuous band of adhesive to one side of the web. The adhesive-coated continuous web, unlike the method disclosed in the Landa and Judge, Jr. prior art, is continuously wound on a rotating stacker. The wound web is removed from the stacker and cut into separate stacks of a desired length.
The present method and apparatus to be described produces in a very efficient and reliable manner, and, in the most preferred form of the invention, monitored and packaged, individual stacks of expandable honeycomb material, and without infringing known patents of others.